redtank

I have reconsidered the capacitor vs. battery solution. I don't want a capacitor exploding inside my control box. I do have a few SLA batteries laying around I can use...20ah capacity. I would rather use a 12v trickle charger to maintain the battery and keep this part of the project separate from other power needs (stepper motor and Arduino). Terry, I don't have an Oscope, but will take your advice and use a suitable diode across the solenoid terminals. As for switching...do you prefer the FET board over using a SSR good for 40 or 60 amps? As you mentioned, pulling 40 amps in 50ms isn't going to happen.

Turn-on time for a DC SSR will be considerable slower than a FET. This might have a bearing on how quickly you can get the required energy into your solenoid, the inductance of which will itself tend to slow down the current in-rush.

Came across these today. U.K supplier :http://www.distel.co.uk/Asps/details1.asp?ID=HP23The coil on these is low current but you could drive them in series from the 24 volts without the 24 to 12 volt conversion and with contacts on the relays in parallelfrom a relatively low power transistor I think.

redtank

Well, I was trying to stay away from a mechanical relay. Received the SSR I ordered from the west coast and it pulls the solenoid in pretty good, only problem is my Arduino doesn't have the power to pull in the SSR! Now I've got to either use a power transistor or reed relay to pull in the SSR..... Just added more complexity to the whole thing.